Security jitters on eve of London Olympics

LONDON — Security jitters were being felt across the British capital on the eve of the London Olympics, with the biggest mall in Europe briefly evacuated Thursday and noticeable security changes in place at the Olympic Park.

Prime Minister David Cameron said, however, that he was confident that the games that Britain has worked to produce for years would be successful and safe.

“You can never provide a 100 percent guarantee, but what I've seen, and what I've helped to coordinate is, I think, a fully joined-up effort that involves one of the best armed services anywhere in the world,” Cameron told reporters Thursday. “I'm confident we can deliver on that, working with visiting delegations as well.”

Hundreds of people flooded into the street, a day before the opening ceremony tonight at nearby Olympic Stadium.

Police allowed shoppers to return after a few minutes.

Westfield mall authorities said the alarm was triggered in a restaurant area.

Fears of terrorism have been at the center of preparations for the London Olympics, and authorities have twice been forced to deploy more troops in the last two weeks — first an extra 3,500, then 1,200 more — when security arrangements fell short.

Britain's Ministry of Defense also scrambled a Typhoon fighter jet Wednesday after an airplane lost contact with air traffic controllers.

Communications were quickly restored, and no further action was required.

Britain's terror threat level is at substantial, which means a terror attack is a strong possibility. It is a notch below severe, the level Britain has been at for most of time since the 2005 suicide bombings when 52 people were killed in morning rush-hour attacks on London trains and buses.

One British security official said there was no existing intelligence to indicate the threat level would change immediately. Several terror suspects have been arrested in the past month, but none have been accused of plotting directly against the games. He spoke on condition of anonymity because he was not authorized to speak to the media.